Presently, portable transceivers of many types including cellular telephones, PCs, laptops, cordless phones, headsets, printers, PDAs, etc., are incorporated into wireless networks. These portable transceivers, such as Bluetooth devices, may contain digital devices to secure fast wireless transmissions of voice or data with worldwide compatibility. As a specification for a small-form factor, low-cost radio solution Bluetooth products may provide links between mobile computers, mobile phones and other portable handheld devices, and connectivity to the Internet. “Bluetooth” refers to a specification to standardize wireless transmission between a wide variety of devices such as PCs, cordless telephones, headsets, printers, PDAs, etc. as is known in the art. Bluetooth creates a single digital wireless protocol to address end-user problems arising from the proliferation of various mobile devices that need to keep data synchronized from one device to another thereby allowing equipment from different vendors to work seamlessly together using Bluetooth as a “virtual cable”.
Bluetooth devices may be named according to a common naming concept. For example, a Bluetooth device may possess a Bluetooth Device Name (BDN) or a name associated with a unique Bluetooth Device Address (BDA). Bluetooth devices may participate in an Internet Protocol (IP) network as well. If a Bluetooth device functions on an IP network, it may be provided with an IP address and an IP (network) name. Thus, a Bluetooth Device configured to participate on an IP network may contain at least one of a BDN, a BDA, an IP address and an IP name.
In the case of Bluetooth devices, communication between devices is commonly accomplished through an Inquiry and Paging procedure that entails a first Bluetooth device emitting an INQUIRY message that is received by all Bluetooth devices within range of the first Bluetooth device. In response to receiving the INQUIRY message, Bluetooth devices may return an INQUIRY_RESPONSE message back to the first Bluetooth device. Upon receiving all of the INQUIRY_RESPONSE messages from neighboring Bluetooth Devices available for communication, the first Bluetooth device selects the device in which connection is desired and sends that device a PAGE message. The connection is typically established upon receipt of a PAGE_RESPONSE message from the receiving Bluetooth device.
In this method, however, the Bluetooth devices must be in the proper mode or scan state for receiving INQUIRY or PAGE messages. These scan states may be referred to as Inquiry_Scan state for receiving inquiry responses and Page_Scan state for receiving pages. Collectively, these states may be referred to as scan states. To receive an INQUIRY message, for example, a Bluetooth device must be in the proper Inquiry_Scan state by tuning to a particular frequency hopping pattern (FHP). Likewise, to receive a PAGE message, a Bluetooth device must be in the proper Page_Scan state. However, when a Bluetooth device is in a Scan state, it cannot form a connection with another device. To form a connection with another device, the Bluetooth device must be in a connected state by tuning to a different FHP, namely the channel hopping pattern (CHP). A Bluetooth Device may only tune to one FHP at a time and therefore may not be in a scan state and a connected state simultaneously as each requires a different FHP.
A Bluetooth device must therefore choose between being in a scan state and being in a connected state. A Bluetooth device may enter a scan state in order to become aware of its surrounding devices. Although when the device enters a scan state, it may not maintain an active connection with other devices. This is because a Bluetooth device may form a connection with another device while in a connected state by tuning to a CHP. The length of time that a device spends in a scan state is referred to as the Scan Dwell Time (SDT). The longer this time is, the more the Bluetooth device loses an opportunity for transmitting user information, degrading the throughput performance of the system. Conversely, the longer the time the Bluetooth device spends in a connected state (referred to as connection dwell time, CDT), the longer the device is able to exchange user information, however during this time the device remains oblivious to surrounding devices that are not already connected, degrading the responsiveness of the device to establishing new connections. This may result in lost opportunities to connect with the Bluetooth device. The frequency in which a device enters a scan state is defined by the scan frequency (SF). A low SF indicates that the originating device does not enter a scan state often and as a result, a second device desiring a connection with the originating device may have to wait before the next time the originating device enters scan state to exchange INQUIRY and PAGE messages. The higher the SF, the longer the wait time.
Therefore, a tradeoff exists such that increasing the CDT while necessarily decreasing the SDT would result in longer connection times, more user data being transmitted and more efficient utilization of the link, however, it would also result in decreased opportunity to connect with other devices. On the other hand, increasing SDT while necessarily decreasing CDT would result in the Bluetooth device spending large amounts of time seeking other devices but less time transmitting actual user information.
Thus, there exists a need in the art for a method and system for providing Scan state operations for devices without limiting the connection of the devices.